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Prince William

Prince Charles stands with his sons Princes William (L) and Harry on the banks of the river Muick near Ballater August 16. The group are currently enjoying a summer break at Balmoral Castle. Reuters/ Jeff J Mitchell UK

Britain's Prince William

Britain's Prince William, the oldest son of Princess Diana and Prince Charles, turned 31 on June 21. The prince, also known as the Duke of Cambridge, is expecting his first child with wife, Catherine Middleton.